A conventional perpendicular magnetic recording and reproducing head of this kind has, as shown in FIG. 12, a structure in which non-magnetic blocks 6 and 6 having a suitable thickness and for providing the opposed surface are joined to the tops of auxiliary magnetic pole blocks 1a and 1b, each of the blocks 1a and 1b having a window 2 for coil winding use, to form a pair of support blocks 4 and 4, a main magnetic pole 3 is held between the pair of support blocks 4 and 4 to form a core chip 1, and the coil is wound through the coil winding windows 2 after the surfaces of the non-magnetic blocks 6 and 6 are polished into a spherical or similar form to be contacted with or opposed to a magnetic recording medium (Patent unexamined publication No. 40314/84 (TOKKAI Sho 59-40314)).
With the magnetic head of the above structure, a magnetic tape, magnetic disk or like magnetic recording medium is driven in sliding contact with or at a predetermined distance from the opposed area A centering about the main magnetic pole 3. Consequently, when a recording signal is applied to the coil and the main magnetic pole 3 is excited accordingly, a magnetic flux is induced from the main magnetic pole 3, by which a magnetic layer of that portion of the perpendicular magnetic recording medium which is being opposed to the upper end face of the main magnetic pole 3 is magnetized in a perpendicular direction. That is, magnetic flux flow circuit is established in which the magnetic flux emanating from the main magnetic pole 3 returns thereto via a route [the magnetic layer of the magnetic recording medium.fwdarw.a soft magnetic layer of the magnetic recording medium.fwdarw.the magnetic layer.fwdarw.an air gap (between the surfaces of the non-magnetic blocks 6, 6 and the magnetic recording medium).fwdarw.the non-magnetic blocks 6, 6.fwdarw.return path portions 1c and 1d of the auxiliary magnetic pole blocks 1a and 1b.fwdarw.main magnetic pole holding portions 1e and 1f]. During reproducing a magnetic flux flow circuit is provided in which a signal current is applied to the coil 5 by a signal recorded in the magnetic layer of the magnetic recording medium via a route reverse from the above-mentioned one for magnetic recording.
In this kind of head, the primary factor that determines its recording and reproducing sensitivity depends on the reluctance of the magnetic flux flow circuit. In other words, the smaller the reluctance is, the more the recording and reproducing sensitivity increases.
In the conventional perpendicular magnetic recording and reproducing head, however, it is difficult to increase the recording and reproducing sensitivity, because the magnetic flux flow circuit includes the air gap and the non-magnetic blocks 6 and therefore has a large reluctance.
To decrease the reluctance, it is also possible, for instance, in the prior art example of FIG. 12, to adopt an arrangement in which the return path portions 1c and 1d of the auxiliary magnetic pole blocks 1a and 1b are directly opposed to the magnetic recording medium with no non-magnetic blocks 6 and 6 interposed therebetween so that the magnetic recording medium is driven in direct sliding contact with or at a predetermined distance from the return path portions. In this instance, however, edges 1g and 1h of the return path portions 1c and 1d are exposed to the magnetic recording medium and perform the function of what is called a pseudo magnetic recording and reproducing gap, inevitably producing an adverse effect of introducing pseudo pulses into the signal output.
Furthermore, if the condition of contact between the magnetic recording medium and the magnetic head, for example, the contact pressure therebetween or the infeed of the magnetic head to the magnetic recording medium, is changed by any unsuspected reason, the distance between the magnetic recording medium and the return path portions 1c and 1d also changes, posing problems such as fluctuations in the output signal level because of the fluctuations of the reluctance.